Power system for a drop hammer



March 25, 1958 W, W slMMONDs 827,764

POWER SYSTEM FOR A DROP HAMMER Filed DecQlz, 1955 2 sheets-sheet `1 1N V EN TOR.

Wayne W /'mmonda /4 TTORNE V5.

March 25, 1958 w. w. slMMoNDs POWER SYSTEM F'OR A DROP HAMMER 2 Sheets-Sheet 2 Filed Dec. 13, 1955 INVEI \l TOR. Way/7e IM zmmonds United States Patent ,I amarsi Ice Patented .Mara 25, 1958 s Claims. (ci. en -si) This invention relates to power hammers of the type generally used for'breaking concrete slabs or other rela- 'tively hard road surfaces or for tamping earth iills, digfgin'g trenches, and other like tasks.

This application is a continuation-in-part of my copending application, Serial No. 305,349, filed August 20,

'1952, and issued January 24, 1956, as Patent No. 2,731,892.

It is'ajprincipal object ofthe invention to provide a L'reciprocating hammer suitable for the above purposes 'Which is powered by a unique combination of hydraulic and'pneumatic forces, and which, as a result, has a. greatly 'improved operational eciency.

It is another object of the invention to provide a power "hammer mounted upon a traveling carriage which can tbe) driven to the site of operations and maneuvered with relative ease while the hammer is being used. In this connection, it is a further object to provide a unique means for mounting the hammer on the carriage so that the'hammer may be adjusted from side to side with respect to the normal path of travel of the carriage and yet maintained in an upright position. Means are also provided for pivoting the hammer with respect to the carriage so that the hammer can be tilted to any desired position independent of the disposition of the carriage. This finds primary advantage in situations where the carriage is resting on uneven terrain or on inclined surfaces.

Still another object is to provide a frame which can be mounted on a conventional tractor to convert the tractor ,into a suitable carriage for the hammer, the parts of the frame also serving as reservoirs for storing the hydraulic and pneumatic fluids which are utilized as power 'sources for'the hammer. lt is also an object to provide suitable pumps on the frame which can be driven concurrently from the power take-od unit of the tractor.

Other and further objects, together with the features of novelty Aappurtenant thereto, will appear in the course "of the following description.

Inthe accompanying drawings which form a part of thespecication andare to be read in conjunction there- "with, land inwhich like reference numerals indicate like partsin the various views,

V`Figfl is aside elevational view of a preferred embodiinen't Vof my invention, the outer wheels being broken faway'for purposes of illustration;

Fig. 2 is `afront elevationalview of the hammer mech- Afariism and support frame, the tractor not being shown;

Fig. -3 is a View taken along the line 3 3 of Fig. l in "thedirectio'n of the arrows;

Fig. lIl is va cross-sectional view taken along the line V4--4 oFg. l in the direction of the arrows;

Fig. '5 is 'a longitudinal sectional view through the hammer cylinder and vertical adjustment cylinder; and

YFig. 6 is a schematic diagram showing the hydraulic- -pneumatic'system for the hammer, and the independent hydraulic system for the vertical adjustment cylinder.

Referring to the drawings, and more particularly to Fig. -1, Athe Vhammer mechanism, generally indicated at 10,--is 'carried `at the forward end of a support frame adapted-to be afxed to a tractor 11, the latter being conventional except that the front wheels have been re- Amoved The basic construction of the frame is shown `Yschematically 'in Fig. 6, and consists principally of two elongated side members 12 and 13 (in the form of hollow, cylindrical tubes) which are jointed to one another fore and aft of the tractor by cross-members 14, 15, and 16 to provide a rigid, unitary structure. These crossmembers are also hollow, cylindrical tubes, and communicate with the side members to form a continuous, air-tight cell which, as will be hereinafter shown, is partitioned and utilized as storage .tanks for both the hydraulic uid and the compressed airused to operate the hammer.

The side members 12 and 13 are disposed on opposite sides of the tractor 11 inside the rear Wheels 17 and as shown clearly in Fig. l, are hung from the rear tractor axle 13 by means of an upper clamping bar 19 resting on top of the axle and connected with the frame member 13 by bolts 2i?. The bolts 20 are carried by a bar 21 welded or otherwise axedto the top of the frame member 13 and bearing against the underside of the axle. It will be understood that while in Fig. 1 only one side of the unit is shown, the method of attachment-just described is the same on both sides.

The second point of attachment of the frame with the tractor is located just rearward of the nose of the latter, and, as in the case of the rear mounting, may be of any suitable construction. The preferred form I have adopted is to weld support brackets 22 to side members 12 and 13, and attach these brackets by bolts or otherwise to the downwardly extending legs 23 of the axle on which the Wheels of the tractor are normally mounted.

To replace the front wheels of the tractor and support the unit at its forward end are two wheels 2li mounted on pin axles 25 which in turn are secured to the ends of a main axle 26 through king pins 27. Axle 26 is centrally pinned to the forward cross-tube 16 by means of a pin 23. A plate 29 (see Fig. 3) spans the side members i2 and 13 intermediate the axle 26 and the cross tube lo, being welded or otherwise secured atfits ends to the side members. This plate serves as additional support for pin 23, which passes therethrough, and also as a bearing plate against which the axle 26 will rub when the unit is passing over rough ground. While not shown in detail, the tractor steering rods 3l) are connected with Wheels 24 through suitable extensions to provide directional control of the unit by operation of the tractor steering-wheel 31.

The forward part of the frame ahead of the nose of the tractor '12 is provided with a flat deck 32 which rests upon and is secured tothe side members i2 and i3 and the forward cross tube i6 to form a door or platform for the operatorofthe hammer. A seat 33 is mounted on this platform and within easy reaching distance of the seat is a bank of valves, generally indicated at V, through which operation `of the unit is controlled. As will be described later, those valves Vin valve bank VV which are identified by specilic reference numerals` play apart in the positioning and operation of the hammer mechanism 1li; the remaining valves are connected with other hydraulic cylinders, for example, suchas that seen at 11 in Fig. l, which are utilized totprovide control over the steering mechanism and transmission of the tractor from the operators chair 33. However, inasmuch as these latter features form no essential vpart of the present invention, they will not be dealt with i-n detail.

Supported at the front end of the frame and between the wheels 2.4 is the hammer mechanism iQ. While the construction andmode of operation of the hammer will be set forth in more detail hereinafter, it Vshould perhaps be noted here that the mechanism comprises a hammer head 34 secured'to the lower end of apiston yshaft 35 which, in operatiomis vertically reciprocated in a cylinder 36 to cause the hammer head v.fait todelive'r a series of impacts to the surface being worked. A guider-rod asume@ communicates with the annular space thus formed between the piston and the packing. A second linev 87 is connected into the top of cylinder 35 to communicate with the space above the piston 84.

The hydraulic and pneumatic system supplying the hammer is shown in Fig. 6. Line 86 at the lower end of cylinder 36 is connected with a three-way valve 59 to which hydraulic duid, such as oil, is pumped by a conventional pump S3 located at the rear of the tractor. The pump 83 draws the tiuid through line 90 as needed, from a reservoir S9 which is formed by the tubular frame member 13. it will be noted that reservoir 89 extends only between cross-members 14 and i5, pressure-tight partitions 9E and 92 being located adjacent the cross-members to form an enclosed compartment wholly within the frame member i3. A return line 93 leads from valve 59 to a secondary reservoir 94 formed by the hollow interior of the hammer-carrying post unit 46, and another line 95 leads from reservoir 94 to the main oil reservoir 89. An air vent 96 is provided near the upper end of the post unit e6 to permit free fluctuation of the uid level therein, the advantage of which will be pointed out hereinafter.

Line 37, which is connected into the upper end of the hammer cylinder 36, communicates at its other end with an air tank 97 formed by the frame side member 12 and the cross-members 14, 2,5, and 16. Compressed air is supplied to tank 97 by a compressor 98 located at the rear of the tractor adjacent the hydraulic pump 88; as is conventional the compressor preferably has a built-in pressure-controlled valve which serves automatically to maintain the pressure in tank 97 at the desiredvalue, approximately 15G p. s. i. Both the compressor and the hydraulic pump are mounted at the rear of the -tractor on opposite sides of the conventional power-take-o pulley 99 and are driven by belts 100 connected therewith.

In describing the operation of the hammer, it will be assumed that the hammer head 34 has been raised Vto its uppermost position, as shown in Figs. l and 6, and that it is ready for the sharp, downward impact stroke. ln this condition, piston 84 is located at the upper limit of its displacement in the hammer cylinder 36, valve 59 having been positioned to supply hydraulic fluid directly from the pump 88 to the line 86 communicating with cylinder 36 below the piston. By virtue of the open communication through line S7, the compressed air in tank 97 exerts pressure on the top of the piston 84 tending to drive the hammer downwardly; however, it will be understood that the pressure of the hydraulic fluid on the underside of the piston is more than suicient to maintain the hammer in the upraised position.

To produce the hammer blow, valve 59 is turned 90 counterciockwise from its Fig. 6 position, which opens communication between the cylinder 36 and post unit 46 through lines 86 and 93. At the same time. the ow from the pump S3 is also diverted into the return line 93, and

accordingly, the pressure inside the cylinder below the piston 84 is completely released.

Under the influence of the air pressure above. the piston Se, the shaft 35 now is driven sharply downward at high speed to cause the hammer head 34 to strike the ground surface or pavement with a hard and sustained impact. The hydraulic uid originally present in the aunular space surrounding shaft 35 is forced outwardly through line 86 by the downward movement of the piston S and into the vertical post unit 46. The primary reason for providing this intermediate reservoir is to eliminate the ow resistance which would otherwise be encountered should line S6 return directly to the oil reservoir 89 in frame memberlS. In other words, the eiciency of the hammer depends in large measure on the rapidity of the downstroke which can be attained. Any resistance to withdrawal of the uid from cylinder 36 has the ultimate eiect of slowing down the action of the hammer, and obviously, a long return line would, by virtue of the frictional iiow resistance therein, serve to amplify this undesirable eti'ect. By providing an intermediate reservoir such as the interior of post unit 46, the iluid leavingfthe cylinder 36 is allowed to accumulate therein after traversing the distance represented by lines S6 and 93, and then to ilow by gravity through line into the reservoir 89 from whence it can be drawn by pump 88 as needed. Since the post unit 46 is vented to atmosphere at 96, the sole resistance to flow out or" cylinder 36 is the fric:- tional resistance in lines d6 and 93 and the relatively small hydrostatic head developed in the post as theuid accumulates.

To raise the hammer for the next stroke, Valve 59is returned to its Fig. 6 position to direct the` ow from pump 8S into the cylinder 36 through line 86; Thehydraulic pressure displaces the piston 84 upwardlyuntil. its fully raised position is reached and the hammer ready for another impact.

As has been pointed out hereinbefore, through the mounting of the hammer mechanism 10 on the pivotal post 46, the hammer may be swung from side to side durf. ing its operation while still maintained substantially vertical. Thus successive impacts can be produced over-a relatively great width without disturbing the line of travel of the tractor itself.

It is also possible to adjust the inclination ofthe hammer mechanism l@ with respect to the ground level or the post 46 by actuating the hydraulic cylinder 78 in the manner hereinbefore described. With this feature, two main advantages over previously known hammers of this general type are obtained. The iirst is fairly obvious, and rests in the ability to align the hammer in a true vertical line even though the tractor is restingI on an incline, i. e., where the wheels on one side of the tractor are at a higher level than those on the other. The second, and less obvious, is that use of cylinder 78, the hammer head 34 can be given a sidewise movement after being imbedded in the ground on the downstroke to rip and tear the earth or break down the walls of a cavity which the hammer is being used to form. ln other words, once the hammer head 34 is imbedded, the operator, through operation of valve Si, can cause cylinder 78 to force the complete hammer mechanism 10 to rotate about the axis of the horizontal spindle 45 and thus impart a side wiseV movement to the hammer head 34. This feature has particular merit where the hammer head 34 isreplaced with another type of tool, sucn as a spade head or digging bucket. in the case of the digging bucket,` the sidewise motion of the hammer produces the scooping effect necessary to remove the earth. v

It will be understood that my hammer'is particularly suitedV to digging trenches of substantial depth. The verti: cal adjustment of the hammer cylinder 36 within its sleeve 4l allows the hammer to be repositioned to a lower level as the dirt is removed from the trench. In other words, as the depth of the cavity increases, the hammer cylinder 36 can be lowered by actuating the Vertical adjustment cylinder 47 positioned alongside sleeve 41. The sleeve 41, of course, remains stationary, the hammer cylinder 36 sliding therein as the piston shaft 51 is displaced downwardly in the adjusting cylinder.

During the transit of the unit from one locationto another, and when the hammer is not in operation, the hammer mechanism 1G can be laid over in a horizontal position, with the upper part of the cylinder 36` resting on a cradle lidi which is supported by legs 162V rising from the frame on opposite sides of thev tractor hood. This is accomplished by removing the retaining pin, 103 from the two-part brace member 43, and swinging the hammer cylinder 3e rearwardly and downwardly about the pin 73 which connects the hammer mechanism to the spindle d5. To ready the hammer for operation, the hammer mechanism lid is returned to its Fig. l position, and pin E03 reinserted in the brace to lock the hammer in its normally upright position.

From the foregoing, it will be seen that I have provided 'if' a mobile hammer unit having both highly eicient operationrand unusual adaptability to various situations which may be encountered in use. Through the unique method of mounting the hammer on the carriage and providing a hydraulic-pneumatic system for operating the hammer independently of the hammer positioning means, a high degree of flexibility in operation is obtained, making the unit readily adaptable to an infinite variety of tasks which have heretofore required'specially designed units not capable ofV use for more than one purpose. My unit is also compact and simple, and as a result extremely economical to manufacture and maintain in repair.

From the'foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the structure.V

It will be understood that certain features and subcornbinations are of utility and may be employed Without reference `to other features andsubcombinations. This is contemplated by and is within the scope of the claims.

As many possbile embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not/'in a limiting sense.

Having thus described my invention, I claim:

1. Fluid actuating means comprising, an enclosed cylinder, a piston reciprocable within said cylinder Vand dividing same into compartments,V a vliquid reservoir, a second reservoir above Vthe liquid reservoir and having an Yair vent in the upper portion thereof, the lower portion of the second reservoir having communication with the liquid reservoir, a gaseous uid reservoir, means for supplying Y gaseous fluid to Ysaid gaseous iiuid reservoir and maintaining'pressure therein within selected limits, said gaseous fluid reservoir Vhaving communication with one compartment of said cylinder adjacent one end thereof remote from the piston whereby the gaseous fluid pressure acts on one end ofthe piston, liquid pressure means operable to move liquid under pressure from the liquid reservoir to theother compartment in said cylinder adjacent the other end thereof with` suicient pressure to effect movement of the piston in said cylinder tov/ard said one end of the cylinder, means withv a iluid passage thereinY connecting said other compartment in said cylinder with the second reservoir for discharge o'fliquid from said other compertinent, andrmeans operable to selectively controlrnovement of liquid to and from said other compartment of Y said cylinder forY effecting movement of the piston therein toward saidvone andsaidother end of the cylinder with the gaseous fluidpressure yaccelerating the movement of i Vtherpiston towardV said 'other end of the cylinder.

' liquid reservoir to' the cylinder to act on the other end ofthe piston with sucient pressure to'eiiectV movement of the piston in said cylinder in one direction, means with a uid passage therein connecting the portion Vof the cylin der. at Vsaid "otherfend'of the piston withthe second Vreservoir, and valve V'control means operable. to selectiveiy control Vmovement of'liquid tol and Yfrom said portion of the` cylinder at the other end of the piston whereby operation of said valve control means to connect the liquid pressureV means Withsaid portion of the cylinder at said other end'of the piston and closing of the passage between said portion of the cylinder at said other end of the pistonand the Vsecond'reservoir provides a supply of liquid pressure which effects Vmovement of the piston in said one direction and operation of the valve control means to stop supply of liquid to said portion of the cylinder at said other end of the piston and opening of the passage from said portion of the cylinder at said other'end of the piston to the second reservoir provides for discharge of liquid from said portion of the cylinder at said other end of the piston which liquid passes through'the second reservoir to the liquid reservoir and the gaseous tluid pressure accelerates the movement of the piston in the other direction. 1

3. Fluid actuating means comprising, an upright enclosed cylinder with an axial opening in its lower end, a piston reciprocable within said cylinder and dividing same into upper and lower compartments, a coaxial shaft secured to said piston and extending downwardlythrough said axial opening, a pressure-tight packing around said shaft in said axial opening forming with the piston an enclosed annular space in said lower compartment, a liquid reservoir, a second reservoir above the liquid reser- Voir and having an air vent in the upper portion thereof, the lower portion of the second reservoir having communication with the liquid reservoir, a gaseous fluid reservoir, means for supplying gaseous uid to 'saidV gaseous duid reservoir and maintaining pressure therein YWithin selected limits, means connecting the gaseous duid Y reservoir with the upper compartment of the'upright cylinder for providing communication therebetween whereby the gaseous uid pressure acts on the upper end of the piston, liquid pressure means operableV to move liquid under pressure from the liquid reservoir to the annular space in the cylinder with suiiicient pressure to eifect upward movement ofthe piston in saidV cylinder, means with a relatively large liuid passage therein connecting the annular space in the cylinder with the second reservoir for quick release of liquid pressure and substantially free falling of said coaxial shaft, and valve control means operable to selectively control movement:V of liquid to and from the annular space of the cylinder whereby operation of said valve control means to connect the liquid pressure means with the annular space and closfV ing of the passage between the annular space and the second reservoir provides a supply of liquid under greater pressure than Vthe gaseous iiuid pressure` acting on the upper endof the piston and the liquid pressurerelects upward movement of the pistonV and shaftV and operation of the valve control means to stop supplyof liquid to the annular space and opening of the passageirom the annular space tothe second reservoir'provides for discharge of liquid from the annular space which liquid passes through the second reservoir to the liquidreservoir and the gaseous lluid present accelerates thedownward movement of the piston and shaft. f

Referns Ci'ed in the le of this partent" Y UNITED STATES PATENTS l'V Great Britain ;`May 11, 19755 ze 

